Z4M Catted Sec 1 Fitment? (Running cats without EGT?)

[ATB88]

It's been brought to my attention that the Z4M has a catted section 1 that fits the E46 M3. Is this correct? Has anyone ever tried fitting these to a euro header setup on an M3? Given the current scarcity of euro cats, this might end up being a good alternate option if they're more widely available on the used market (big if).

see here at ECS: https://www.ecstuning.com/b-genuine-...18307836634kt/

If they fit, my biggest concern would be that they don't look like they have a bung for EGT sensor. How big of a risk is it to run cats without an EGT sensor? Does anyone know if the actual catalytic converter found in a Z4M sec 1 is identical to what you'd find in a euro section 1 (size and cell count)?

[ATB88]

Huh, so, according to RealOEM, the Z4M has two sets of cats: one in the headers and one in the sec1... is that right? or am I just misinterpreting and there were two versions (like US and Euro for M3)? https://www.realoem.com/bmw/enUS/par...W-Z4_M32&mg=18

And according to RealOEM the section has bungs for post-cat O2 and EGT sensors, but, the part pictured at ECS has no bungs... what up with that?

[heinzboehmer]

I've never been under a Z4M, but by looking at pictures online and on RealOEM, it seems like the triangular clamp connector things are clocked differently on the Z4M than on the M3 (two bolts on the bottom for Z4M vs two bolts on top for M3). Also, RealOEM shows an EGT sensor on the Z4M section 1, so that should be fine.

https://www.realoem.com/bmw/enUS/sho...diagId=18_0658
https://www.realoem.com/bmw/enUS/sho...diagId=18_0659

Regardless, you would need to chop it and weld it to make it fit, so might as well buy some quality cats and weld them to your existing section 1 instead.

[Titaniu//M]

According to people on Zpost, E46 M3 euro cats do not fit a Z4M, so I do not believe the reverse can be done either.

https://www.zpost.com/forums/showthread.php?t=855852

https://www.zpost.com/forums/showthread.php?t=473167

[Zekarus]

just for your information I'm running euro cats without post o2 and egt sensors. no issues. they where disabled on the ecu too. according to some on the old m3f these sensors are only for cat efficiency. that said you won't know if the cats have any issue. at least the ecu won't tell you.

[ATB88]

Yeah okay the flanges won't line up, rip.

This could have been a nice solution to the euro cat shortage, but then if it were I'm sure someone would have discovered it by now lol.